Duck experts nervous about fall migration to Gulf

Wednesday

Jun 16, 2010 at 12:01 AMJun 16, 2010 at 4:15 PM

Millions of ducks could fly into trouble when they arrive at their wintering grounds this fall. About 13 million ducks spend the winter on the coast of the Gulf of Mexico, the area that has been hard hit by the massive oil spill.

Chris Young

Millions of ducks could fly into trouble when they arrive at their wintering grounds this fall.

According to Ducks Unlimited, 13 million ducks spend the winter on the coast of the Gulf of Mexico, the area that has been hard hit by the massive oil spill caused by the sinking of the Deepwater Horizon drilling rig.

Teal, among the first ducks to migrate, will be on their way as soon as August.

A veritable gusher of birds will follow, including up to 1.5 million scaup, a waterfowl species that has been declining steadily in numbers for 30 years.

“We don’t know where this oil is going to end up, so it is hard to plan a response,” said Tom Moorman, director of conservation for the southern region of Ducks Unlimited. “We don’t have a lot of time.”

No one knows for sure what the ducks will find when they arrive, but one thing is certain: There is no way to stop them from migrating.

Moorman said the southeast coast of Louisiana is the winter home to about 4.7 million ducks, by far the most on the Gulf coast. Coastal Mississippi hosts about 20,000 ducks, as does Mobile Bay, Ala. The Panhandle of Florida to about Tampa Bay will see about 100,000 ducks, 80,000 of them redhead ducks.

“Our biggest concern are scaup, particularly lesser scaup,” Moorman said. A survey conducted from 2000 to 2002 showed between 250,000 and 1.4 million scaup off the coast of Louisiana.

“Birds do move around quite a bit,” Moorman said. “But still, that (top number) equates to 30 percent of the population of that species potentially affected by oil.”

Food supply impact

Besides the threat of being covered by oil, scaups’ food supply could be affected, too. Scaup are diving ducks that like to feed on the dwarf surf clam, which is no larger than a thumbnail.

“There are concerns about the clams as a food source and that they could be killed outright,” Moorman said. “That (a lack of food) could scatter the birds to the wind in search of new habitat.”

Fortunately, many other species of ducks prefer freshwater marshes with very low salinity located just inland.

“Brackish and salt marsh are important for some other birds, but not so much for ducks,” he said.

However, the potential is there for a storm surge to push salt water — and possibly oil — into the marshes.

“I keep using the ‘potential’ word because there is so much oil off shore,” Moorman said. “But despite what you’re seeing on the news, there is not so much oil getting into the really good duck habitat.

“We’ll just have to see. If it gets into the interior marshes, then we’re in trouble.”

To compensate, plans are under way to flood habitat adjacent to the marsh.

“The goal is to provide alternative foraging habitat,” Moorman said. “But these are wild birds, and most are going to the marsh if they want to.

“We hope they will stay out of the oiled areas.”

Hunting season

Bo Arnold, president of the Illinois Federation for Outdoor Resources, a sportsmen’s advocacy group, said he isn’t aware of any movement yet to shorten duck-hunting seasons to compensate for possible duck losses

“You can’t do that until you see what happens,” Arnold said. “The animals may be smarter than we think they are and they stay away (from oiled areas).”

Moorman said high water on the Mississippi River so far is keeping oil out of some refuges, like the Pass-a-Loutre Wildlife Management Area along the mouth of the river.

The refuge shelters more than 200,000 ducks during the winter.

“If the river drops, oil could get in and kill food sources,” he said. “It really depends upon whether or not the oil persists.”

Likewise, so far it doesn’t look like the oil is headed for the western part of the Louisiana coast, which would put another 4.5 million ducks at risk.

Ducks also have one thing in their favor, the ability to adjust to changing habitat conditions, Moorman said.

“They have evolved over millennium to rely on wetlands that are (sometimes temporary) in nature,” he said. “They are here today and gone tomorrow.

“If ducks weren’t responsive to dynamic habitats, there would be a lot fewer ducks,” Moorman said. “Ducks would be in a world of hurt — and so would we.”

Chris Young can be reached at 217-788-1528.

Coastal marshes already under stress

Louisiana’s coastal marshes were under stress before the Deepwater Horizon oil spill, largely due to manmade changes that have altered the flow of water and the way sediment is deposited.

A study released by the Gulf Coast Joint Venture, a coalition of scientists from Gulf Coast states from Alabama to Texas, says the marshes are losing their ability to provide enough food for wintering waterfowl. The region can sustain 3 million fewer ducks than it could in the 1970s.

Changes in water flow have interrupted the equilibrium between land building and erosion.

“That’s it in a nutshell,” said Tom Moorman, director of conservation for the southern region of Ducks Unlimited.

Levees, drainage projects and other development have starved some areas of sediment, causing them to erode away, the study found.

Moorman said Louisiana’s wetlands are disappearing at the rate of 16,000 to 20,000 acres per year. About 1.2 million acres have been lost in the last 70 years.

Typically, deltas form when rivers reach the sea and spread out in multiple braided channels. Whenever the river changes course, new areas are built up while the older areas are eroded away.